Lung Capacity Calculator
Calculate total lung capacity, vital capacity, and other respiratory volumes from spirometry data
Medical Disclaimer
This calculator is for educational purposes only and cannot replace professional medical assessment.
- Results are based on entered spirometry values and general population norms
- Normal ranges vary significantly with age, sex, height, ethnicity, and individual factors
- Always consult a pulmonologist or respiratory therapist for proper interpretation
- This tool cannot diagnose respiratory conditions or replace clinical evaluation
Lung Volume Measurements
Extra air inhaled after normal inspiration
Air volume during normal breathing at rest
Extra air exhaled after normal expiration
Air remaining in lungs after maximum expiration
Calculated Lung Capacities
Enter all lung volumes to calculate capacities
IRV, TV, ERV, and RV are all required for accurate calculations
Example Calculation
Normal Adult Example (in Liters)
Input Volumes:
• IRV = 3.0 L
• TV = 0.5 L
• ERV = 1.0 L
• RV = 1.2 L
Calculated Capacities:
• TLC = 3.0 + 0.5 + 1.0 + 1.2 = 5.7 L
• VC = 3.0 + 0.5 + 1.0 = 4.5 L
• IC = 3.0 + 0.5 = 3.5 L
• FRC = 1.0 + 1.2 = 2.2 L
Interpretation: All values within normal ranges for a healthy adult
Lung Volume Definitions
IRV - Inspiratory Reserve Volume
Maximum air inhaled after normal inspiration (~3000 mL)
TV - Tidal Volume
Air breathed in/out during normal quiet breathing (~500 mL)
ERV - Expiratory Reserve Volume
Maximum air exhaled after normal expiration (~1000 mL)
RV - Residual Volume
Air remaining in lungs after maximum expiration (~1200 mL)
Normal Ranges (Adults)
TLC
5-7 L (5000-7000 mL)
VC
3-5 L (3000-5000 mL)
IC
2-4 L (2000-4000 mL)
FRC
~2 L (~2000 mL)
Clinical Applications
Spirometry Analysis
Essential for pulmonary function testing
Disease Monitoring
Track progression of respiratory conditions
Surgical Planning
Assess respiratory reserves pre-operatively
Disability Assessment
Evaluate functional impairment
Understanding Lung Capacities
Calculation Formulas
Total Lung Capacity (TLC)
TLC = IRV + TV + ERV + RV
Complete air volume in lungs
Vital Capacity (VC)
VC = IRV + TV + ERV
Maximum expellable air volume
Inspiratory Capacity (IC)
IC = IRV + TV
Maximum inhalable air volume
Functional Residual Capacity (FRC)
FRC = ERV + RV
Air remaining during relaxed breathing
Clinical Significance
Restrictive Patterns
Reduced lung volumes and capacities may indicate conditions like pulmonary fibrosis, chest wall deformities, or neuromuscular disorders.
Typically: ↓TLC, ↓VC, ↓IC, ↓FRC
Obstructive Patterns
Air trapping and hyperinflation seen in conditions like COPD and asthma, with increased residual volumes.
Typically: ↑TLC, ↑FRC, ↑RV, variable VC
Mixed Patterns
Combination of restrictive and obstructive changes, requiring careful clinical correlation and additional testing.
Factors Affecting Lung Capacity
Physical Factors
- • Age (decreases with age)
- • Height (taller = larger capacity)
- • Sex (males typically larger)
- • Physical fitness level
Environmental
- • Altitude (adaptation occurs)
- • Air pollution exposure
- • Occupational hazards
- • Smoking history
Medical Conditions
- • Respiratory diseases
- • Cardiac conditions
- • Neuromuscular disorders
- • Chest wall abnormalities